Flavor of the Month
Flavor of the Month or FotM is an expression that refers to a profession combination, skill, or build that is currently very popular in the metagame. The expression also denotes that the interest is temporary, since the more players use one setup, the more likely others will be to bring direct counters. FotM are often named by adding "-way" to the build's main idea in jest, referring to one of the most infamous FotMs: IWAY.
Because of the mechanics of Guild Wars, if a FotM becomes too popular, it becomes viable to carry counters targeting that one specific build. This will, over time, shift a FotM out of play. However, if a FotM becomes too popular for too long or proves to be too imbalanced, it becomes the target of a nerf by ArenaNet.
FotM usually applies to PvP, since generally the only counter to a PvE build is a nerf by ArenaNet.